Family Delphinidæ — The Dolphins or Porpoises
Genus Platanista — The River Dolphins
A globular head with a long, compressed and, towards the end, spoon-shaped rostrum or snout; flippers short, broad and triangular; a long body of moderate girth; no back fin, but a slight elevation which takes its place. There is a decided depression between the head and body on the region of the neck; the eye is remarkably small, so much so as to be hardly perceptible; in an adult of eight feet long the whole eye-ball is no bigger than a pea, and the orifice of the ear is like a pin-hole.
The skull has peculiar features. “The apparently rounded skull behind the snout has broad, thick zygomatic arches, and above and in front of these the cheek-bones (maxillæ) each send forwards and inwards a great roughened sheet of bone or crest, which forms a kind of open helmet. In the large hollow between these bony plates, and somewhat behind, are situated the nasal orifices, which are slightly awry” (Murie).[19] Professor Flower’s notice of the skull (‘Osteology of the Mammalia’) is thus worded: “The orbit is extremely small, the temporal fossa large, and the zygomatic processes of the squamosal are greatly developed. From the outer edge of the ascending plates of the maxillæ, which lie over the frontals, great crests of bone, smooth externally, but reticulated and laminated on their inner surface, rise upwards, and, curving inwards, nearly meet in the middle line above the upper part of the face.”
19 See Appendix B for illustration.
The dentition is also curious, the upper and lower jaws being provided with a number of teeth, pointed and conical in front, and smaller and more flattened behind. They vary in number. In an example quoted by Dr. Murie the total was 117, viz., 27—28/30—32, but in a specimen examined by Dr. Anderson, who has most exhaustively described these animals, the total number of teeth amounted to 128, i.e. 33—32/32—31. (See Appendix B.)
The cervical vertebræ are movable, and not ankylosed, as in many of the cetacea; the cæcum is small; the blow-hole is a narrow slit, not transverse as in other whales, but longitudinal. I have somewhat gone out of order in Jerdon’s numbering in bringing in this genus here instead of letting it follow Delphinus, as he has done. These river Dolphins naturally come after the extinct Phocodontia or seal-toothed whales, and bear considerable resemblance in the dentition to the extinct genus Squalodon.
No. 257. Platanista Gangetica.
The Gangetic Porpoise (Jerdon’s Nos. 144 and 145).
Native Names.—Soonse, Soosoo, Soosa, Hindi; Susak, Shishuk, Bengali; Sisumar, Sanscrit; Bulhan or Sunsar, on the Indus; Hihoo, Siho; Assamese; Huhh in Cachar and Sylhet.
Habitat.—In the larger rivers connected with the Ganges nearly up to the hills; also in the Brahmaputra and in the Indus, but in fresh water; only it does not go out to sea.
Description.—“A long compressed snout with a formidable array of teeth; a vaulted compressed forehead; longitudinal blow-hole; scarcely perceptible eye; distinct neck; broad and abruptly truncated pectoral fins, and small dorsal fin; and the male, a smaller but heavier-built animal than the female, with a shorter snout” (Anderson). The colour is from a dark lead to a sooty black; according to Jerdon “when old with some lighter spots here and there; shining pearl-grey when dry.”
Size.—From six to eight feet.
This animal, though not often captured, at all events in the vicinity of Calcutta, is familiar to most people who have travelled on the larger Indian rivers. It is common enough in the Hooghly. I have frequently observed it in the river abreast of the Fort whilst we were slowly driving down the Course.
I am largely indebted to Dr. Anderson for information concerning it, for he has not only most carefully watched the habits of this curious animal, but has most exhaustively described its anatomy in his ‘Anatomical and Zoological Researches.’ It is found in the Hooghly, chiefly in the cold weather, migrating during the hot and rainy season; at least so it was supposed, and Dr. Cantor conjectured that at such times it visited the sea, but this has been proved to be not the case. The soosoo never leaves fresh water; and it is in the river during the rains, for fishermen catch it in their nets, but it is hardly ever seen at that time. It rises so as to expose the blow-hole only, and the rush of the swollen waters prevents the peculiar sound of respiration being heard. But in the cold weather, when the river is calm, the ear is attracted at once by the hissing puff of expiration, and the animal may be seen to bound almost out of the water. Dr. Anderson had one alive in captivity for ten days, and carefully watched its respirations. “The blow-hole opened whenever it reached the surface of the water. The characteristic expiratory sound was produced, and so rapid was the inspiration that the blow-hole seemed to close immediately after the expiratory act.” He states that “the respirations were tolerably frequent, occurring at intervals of about one-half or three-quarters of a minute, and the whole act did not take more than a few seconds for its fulfilment.” But it is probable that in a free state and in perfect health the animal remains longer under water. It has certainly been longer on several occasions when I have watched for the reappearance of one in the river. The food of the Gangetic dolphin consists chiefly of fish and crustacea; occasionally grains of rice and remains of insects are found in the stomach, but these are doubtless, as Dr. Anderson conjectures, in the fish swallowed by the dolphin. The period of gestation is said to be eight to nine months, and usually only one at a time is born, between April and July. The young are sometimes caught with their mothers, and are said to cling by holding on by the mouth to the base of the parent’s pectoral fins. “The flesh and blubber are occasionally eaten by many of the low caste Hindus of India, such as the Gurhwals, the Domes of Jessore and Dacca districts, the Harrees, Bourees, Bunos, Bunpurs, Tekas, Tollahas, the Domes of Burdwan and Bhagulpore, who compare it to venison; also by the Teewars and Machooas of Patna, the Mussahars of Shahabad, the Gourhs and Teers of Tirhoot, and the Mullahs of Sarun. In the North-west Provinces about Allahabad, the Chumars, Passees, Kooras, Khewuts or Mullahs, have rather a high estimate of the flesh, which they assert resembles turtle. The Koonths of Benares, Phunkeahs, Natehmurrahs, and Buahoas of Moradabad, and also such gipsy tribes as the Sainsees, Kunjars and Hubbossahs, in the neighbourhood of Meerut, do not despise it. In the Punjab we find the Choorahs, Dhapels, Sainsees, Budous, and Burars eating the flesh; and in Sind the Kehuls. The Moras, a tribe of Mahomedan boatmen who lead a wandering life on the streams in the Punjab and in Sind, subsist on the dolphin when by good chance they catch one; this is also the case with the Cacharies and the Nagas of Assam. The Sansee women on the Indus eat the flesh under the idea that it makes them prolific. All along the Ganges, Brahmahputra, and Indus, the oil is universally considered as of great value as an embrocation in rheumatism and for giving much strength when rubbed on the back and loins. But many other animal oils, such as those of various species of turtle, the crocodile, and the pelican, have a similar reputation. It is said to be of a very penetrating nature, and, owing to this property, it is highly prized for preserving leather, such as harness, &c. The illuminating powers of this oil are said to be very high.” (Anderson’s ‘Anatomical and Zoological Researches.’)
Jerdon gives, on the authority of Blyth, another species, Platanista Indi, or the Indus porpoise, but Dr. Anderson has conclusively proved that this is identical with the Gangetic dolphin. The dentition of the soosoo is most curious. The perfect tooth in the young animal is sharp and pointed, but as the creature advances in age the fangs get broader, and the point wears down, till in old age the crown is so worn as to leave but a bony lump in its place.
← Back to Natural History of the Mammalia of India and Ceylon